How can I validate with many options in a program? ?

Question

Am having a program that has a lot of options and each option... I need to validate if the input is correct. .any help??..
https://code.sololearn.com/cB2lHRXFQKL1/?ref=app

Answer 1

int main()
{
int _option; <= put this here
do
{
<= and not here!

Answer 2

Let me try it out and see...